1. Field of the Invention
The present invention relates generally to exercise machines and systems for providing resistive force exercise to the user. The present invention relates more specifically to an exercise machine structured to provide a consistent force resisting the ambulatory (walking and/or running) motion of a user moving away from and then back towards the machine.
2. Description of the Related Art
Many exercise regimens call for the repeated movement of the exercising individual from a first point to a second point, typically across a gym floor or across an outdoor field. In some cases this movement is simply a straight line run from one point to the next. In some cases the movement involves weaving around cones or other small obstacles in the path. Some efforts have been made in the past to increase the strength and/or energy required to make this movement by securing a weight to the exercising individual that must be pulled along during the exercise. One such effort in the past has been to provide a weight sled that may be connected to the exercising individual by a line (a cord or a rope) and is drug along the ground by the individual as they attempt to run. Clearly the process of dragging such a weight sled across a floor surface indoors can be problematic.
Even when used outdoors, the typical weight sled offers a very inconsistent resistive force to the user and often results in intervals of high resistance (where the sled sticks or digs into the ground) followed by intervals of very little resistance (where the sled looses contact with the ground and jumps a distance).
A further effort in the past to provide additional resistive force to an exercising individual replaces the sliding weight sled with a fixed but stretchable “bungee cord” line attached to a fixed anchor and to a harness on the individual. Rather than provide a consistent resistive force, however, such systems provide an initial weak force that gradually increases to very strong force. This often results in the individual being awkwardly jerked backwards at the end of the exercise motion. Many injuries have resulted from the use of both types of resistance exercise systems.
It would be desirable to provide a resistance exercise system that could be easily used indoors or outdoors without concern for damaging the indoor floor surface or the outdoor turf. It would be desirable if the system provided a generally consistent resistive force rather than one that dramatically increased during the exercise or one that provided a resistive force in jerking catches and releases. It would further be desirable if such a system provided a gradual but consistent recoil at the end of the exercise so as to allow the user to return casually to the starting point of the exercise to complete the workout or to start the exercise again.
It would further be desirable to provide a mechanism for adjusting the resistive force exerted against the user during the exercise and to provide an easy and accurate means for indicating the level of the resistive force. It would be beneficial if the resistive force exercise device were capable of easily resetting itself without tangling or damaging the line attached between the device and the user.